Method to dynamically change the minimum candidate resources ratio in mode 2 resource selection procedure of nr v2x

ABSTRACT

Method of resource selection where a selection window with a total number of resources is set. The method includes setting a sensing window and monitoring slots by decoding a physical sidelink control channel (PSCCH) and measuring a reference signal received power (RSRP), setting a threshold, excluding any restricted resources from the total number of resources, excluding any occupied resources from the total number of resources, and determining if an initial number of remaining resources is greater than or equal to an initial percentage of the total number of resources.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. Pat. Application No.17/226,957 filed on Apr. 9, 2021, which claims the benefit of U.S.Provisional Pat. Application No. 63/021,073 filed on May 6, 2020 in theUnited States Patent and Trademark Office, the entire contents of eachof which are herein incorporated by reference.

FIELD

The present disclosure is generally related to. In particular, thepresent disclosure is related to Mode 2 Resource selection in New Radio(NR) Vehicle to Everything (V2X).

BACKGROUND

In NR V2X, Step 1 of the Mode 2 resource selection procedure provides aset of resources for higher layer that can be used for transmission. InStep 2, the transmission resources are selected randomly by the higherlayer. Hence, to reduce the probability of collision, there exists aminimal ratio X% between the resources passed to Step 2 and the totalavailable resources within the resource selection window. This conceptwas adopted from LTE wherein the ratio, X%, is set to 20%. However,unlike LTE, NR V2X involves both periodic and aperiodic traffic and isexpected to require stringent latency and reliability requirements.Hence, it is necessary to 1) allow the system to have different valuesof X% based on priority to guarantee the reliability; and 2) allow thesystem to dynamically change the value of X% within Step 1 of the Mode 2resource selection procedure to avoid passing resources that wouldresult in collisions to the higher layers.

SUMMARY

A method of resource selection, the method comprising: setting, by auser equipment (UE), a selection window; setting, by the UE, a sensingwindow and monitoring slots by decoding a physical sidelink controlchannel (PSCCH) and measuring a reference signal received power (RSRP);setting, by the UE, a threshold; defining a set of a total number ofresources based on the selection window; excluding based on the sensingwindow, by the UE, any restricted resources from the total number ofresources; excluding based on the threshold, by the UE, any occupiedresources from the total number of resources; and determining, by theUE, if an initial number of remaining resources is greater than or equalto an initial percentage of the total number of resources.

The method comprising reporting the number of remaining resources to ahigher layer when the initial number of remaining resources is greaterthan or equal to the initial percentage of the total number ofresources.

The method comprising at least one iteration including: increasing thethreshold, when the initial number of remaining resources is less thanthe initial percentage of the total number of resources, andredetermining if a subsequent number of remaining resources is greaterthan or equal to a subsequent percentage of the total number ofresources.

The method wherein the subsequent percentage varies for each iteration,wherein a factor by which the subsequent percentage changes depends onan iteration number or a transmission priority.

The method wherein the subsequent percentage varies for each iteration,wherein the subsequent percentage is selected from a preconfigured set.

The method wherein the subsequent percentage varies for each iteration,wherein a factor by which the subsequent percentage changes depends on aCBR or a ratio between aperiodic and periodic traffic.

The method wherein the resource selection window is divided into atleast a first section with a first percentage and a second section witha second percentage, wherein the first percentage and the secondpercentage vary in each iteration, respectively.

The method wherein the subsequent percentage varies for each iteration,wherein the subsequent percentage is selected, from a preconfigured set,based on a traffic priority.

The method wherein the occupied resources are occupied by a UE and thecorresponding RSRP of the occupied resources is greater than or equal tothe threshold.

The method wherein the resource selection window is divided into atleast a first section with a first percentage and a second section witha second percentage.

A system for resource selection, comprising: a processor; and a memorystoring non-transitory processor-executable instructions that, whenexecuted by the processor, cause the processor to: set a selectionwindow; set a sensing window and monitoring slots by decoding a physicalsidelink control channel (PSCCH) and measuring a reference signalreceived power (RSRP); set a threshold; define a set of a total numberof resources based on the selection window; exclude, based on thesensing window, any restricted resources from the total number ofresources; exclude, based on the threshold, any occupied resources fromthe total number of resources; and determine if an initial number ofremaining resources is greater than or equal to an initial percentage ofthe total number of resources.

The system comprising reporting the number of remaining resources to ahigher layer when the initial number of remaining resources is greaterthan or equal to the initial percentage of the total number ofresources.

The system comprising at least one iteration including: increasing thethreshold, when the initial number of remaining resources is less thanthe initial percentage of the total number of resources, andredetermining if a subsequent number of remaining resources is greaterthan or equal to a subsequent percentage of the total number ofresources.

The system wherein the subsequent percentage varies for each iteration,wherein a factor by which the subsequent percentage changes depends onan iteration number or a transmission priority.

The system wherein the subsequent percentage varies for each iteration,wherein the subsequent percentage is selected from a preconfigured set.

The system wherein the subsequent percentage varies for each iteration,wherein a factor by which the subsequent percentage changes depends on aCBR or a ratio between aperiodic and periodic traffic.

The system wherein the resource selection window is divided into atleast a first section with a first percentage and a second section witha second percentage, wherein the first percentage and the secondpercentage vary in each iteration, respectively.

The system wherein the subsequent percentage varies for each iteration,wherein the subsequent percentage is selected, from a preconfigured set,based on a traffic priority.

The system wherein the occupied resources are occupied by a UE and thecorresponding RSRP of the occupied resources is greater than or equal tothe threshold.

The system wherein the resource selection window is divided into atleast a first section with a first percentage and a second section witha second percentage.

BRIEF DESCRIPTION OF THE DRAWINGS

The patent or application file contains at least one drawing executed incolor. Copies of this patent or patent application publication withcolor drawing(s) will be provided by the Office upon request and paymentof the necessary fee.

The above and other aspects, features, and advantages of certainembodiments of the present disclosure will be more apparent from thefollowing detailed description, taken in conjunction with theaccompanying drawings, in which:

FIG. 1 illustrates a diagram of a resource selection window according tosome embodiments;

FIG. 2A illustrates a flowchart for resource selection according to someembodiments;

FIG. 2B illustrates another flowchart for resource selection accordingto some embodiments;

FIG. 3A illustrates a flowchart for Mode 2 resource selection accordingto some embodiments;

FIG. 3B illustrates a flowchart for a resource selection procedureaccording to some embodiments;

FIG. 4 illustrates another flowchart for a resource selection procedureaccording to some embodiments; and

FIG. 5 illustrates an example block diagram of an electronic device andnetwork environment for implementing a Mode 2 resource selectionprocedure according to some embodiments.

DETAILED DESCRIPTION

Hereinafter, embodiments of the present disclosure are described indetail with reference to the accompanying drawings. It should be notedthat the same elements will be designated by the same reference numeralsalthough they are shown in different drawings. In the followingdescription, specific details such as detailed configurations andcomponents are merely provided to assist with the overall understandingof the embodiments of the present disclosure. Therefore, it should beapparent to those skilled in the art that various changes andmodifications of the embodiments described herein may be made withoutdeparting from the scope of the present disclosure. In addition,descriptions of well-known functions and constructions are omitted forclarity and conciseness. The terms described below are terms defined inconsideration of the functions in the present disclosure, and may bedifferent according to users, intentions of the users, or customs.Therefore, the definitions of the terms should be determined based onthe contents throughout this specification.

The present disclosure may have various modifications and variousembodiments, among which embodiments are described below in detail withreference to the accompanying drawings. However, it should be understoodthat the present disclosure is not limited to the embodiments, butincludes all modifications, equivalents, and alternatives within thescope of the present disclosure.

Although the terms including an ordinal number such as first, second,etc. may be used for describing various elements, the structuralelements are not restricted by the terms. The terms are only used todistinguish one element from another element. For example, withoutdeparting from the scope of the present disclosure, a first structuralelement may be referred to as a second structural element. Similarly,the second structural element may also be referred to as the firststructural element. As used herein, the term “and/or” includes any andall combinations of one or more associated items.

The terms used herein are merely used to describe various embodiments ofthe present disclosure but are not intended to limit the presentdisclosure. Singular forms are intended to include plural forms unlessthe context clearly indicates otherwise. In the present disclosure, itshould be understood that the terms “include” or “have” indicateexistence of a feature, a number, a step, an operation, a structuralelement, parts, or a combination thereof, and do not exclude theexistence or probability of the addition of one or more other features,numerals, steps, operations, structural elements, parts, or combinationsthereof.

Unless defined differently, all terms used herein have the same meaningsas those understood by a person skilled in the art to which the presentdisclosure belongs. Terms such as those defined in a generally useddictionary are to be interpreted to have the same meanings as thecontextual meanings in the relevant field of art, and are not to beinterpreted to have ideal or excessively formal meanings unless clearlydefined in the present disclosure.

The electronic device according to one embodiment may be one of varioustypes of electronic devices. The electronic devices may include, forexample, a portable communication device (e.g., a smart phone), acomputer, a portable multimedia device, a portable medical device, acamera, a wearable device, or a home appliance. According to oneembodiment of the disclosure, an electronic device is not limited tothose described above.

The terms used in the present disclosure are not intended to limit thepresent disclosure but are intended to include various changes,equivalents, or replacements for a corresponding embodiment. With regardto the descriptions of the accompanying drawings, similar referencenumerals may be used to refer to similar or related elements. A singularform of a noun corresponding to an item may include one or more of thethings, unless the relevant context clearly indicates otherwise. As usedherein, each of such phrases as “A or B,” “at least one of A and B,” “atleast one of A or B,” “A, B, or C,” “at least one of A, B, and C,” and“at least one of A, B, or C,” may include all possible combinations ofthe items enumerated together in a corresponding one of the phrases. Asused herein, terms such as “1^(st),” “2nd,” “first,” and “second” may beused to distinguish a corresponding component from another component,but are not intended to limit the components in other aspects (e.g.,importance or order). It is intended that if an element (e.g., a firstelement) is referred to, with or without the term “operatively” or“communicatively”, as “coupled with,” “coupled to,” “connected with,” or“connected to” another element (e.g., a second element), it indicatesthat the element may be coupled with the other element directly (e.g.,wired), wirelessly, or via a third element.

As used herein, the term “module” may include a unit implemented inhardware, software, or firmware, and may interchangeably be used withother terms, for example, “logic,” “logic block,” “part,” and“circuitry.” A module may be a single integral component, or a minimumunit or part thereof, adapted to perform one or more functions. Forexample, according to one embodiment, a module may be implemented in aform of an application-specific integrated circuit (ASIC).

In Fifth Generation (5G) New Radio (NR) Vehicle to Everything (V2X),Mode 2 resource allocation procedure is used for sidelinkcommunications. In this procedure, two steps are applied (Step 1 to finda set of resources with low chances of collisions and Step 2 to randomlyselect one or more of these resources). There exists a requirement onthe minimum number of resources that need to be passed to Step 2 (i.e.,X% where X is the ratio between the resources obtained from step 1 tothe total number of available resources). Mode 2 resource selection maybe used by User Equipments (UEs) to select resources for transmission.In this mode, the UEs define a sensing window and a resource selectionwindow. In the sensing window, the UEs identify the resources (withinthe resource selection window) that are reserved by neighboring UEs.This is done by decoding the received Sidelink Control Information (SCI)within the sensing window, and accordingly identifying the indicatedresources for future transmissions. The resources indicated by the SCIsare considered to be occupied if the Reference Signal Received Power(RSRP) corresponding to an SCI is above a certain RSRP threshold. Thethreshold may be based on a priority indicated by the SCI. The resourcesindicated by an SCI are excluded from the resource selection window ifthe RSRP is above a certain threshold.

In resource allocation Mode 2, the higher layer can request the UE todetermine a subset of resources from which the higher layer will selectresources for PSSCH/PSCCH transmission. To trigger this procedure, inslot n, the higher layer provides the following parameters for thisPSSCH/PSCCH transmission:

-   the resource pool from which the resources are to be reported;-   L1 priority, prio_(TX);-   the remaining packet delay budget;-   the number of sub-channels to be used for the PSSCH/PSCCH    transmission in a slot, L_(sub)CH;-   optionally, the resource reservation interval, P_(rsvp) _(_) _(TX),    in units of ms.

The following higher layer parameters affect this procedure:

-   t2min_SelectionWindow: internal parameter T_(2min) is set to the    corresponding value from higher layer parameter t2min    SelectionWindow for the given value of prio_(TX).-   SL-ThresRSRP_pi_pj: this higher layer parameter provides an RSRP    threshold for each combination (p_(i), p_(j)), where p_(i) is the    value of the priority field in a received SCI format 0-1 and p_(j)    is the priority of the transmission of the UE selecting resources;    for a given invocation of this procedure, p_(j) = prio_(TX).-   RSforSensing selects if the UE uses the PSSCH-RSRP or PSCCH-RSRP    measurement, as defined in subclause 8.4.2.1.-   reservationPeriodAllowed-   t0 SensingWindow: internal parameter T₀ is defined as the number of    slots corresponding to t0_SensingWindow ms.-   The resource reservation interval, P_(rsvp_TX), if provided, is    converted from units of ms to units of logical slots, resulting in-   P^(′)_(rsvp_TX).-   Notation:-   (t₀^(SL), t₁^(SL), t₂^(SL), …)-   denotes the set of slots which can belong to a sidelink resource    pool.

To ensure that the UE can support the value of X, the UE might need tosignificantly increase its threshold levels thus potentially creatinginterference to its neighboring high priority. The interference may alsobe magnified when the resource selection window is not sufficientlylong. Additionally, processing burden might be added to the UE as the UEmight perform the resource selection procedure multiple times until theminimum requirement for the ratio is met. At the same time, reducing thevalue of X may result in collisions between UE transmissions as limitedresources will be available for resource selection by higher layers.Additionally, if the ratio is required to be maintained for a portion ofthe resource selection window (i.e., a new ratio is defined between theavailable resources within the duration that can be indicated by the SCIto the total number of resources within the same duration), it mayresult in significantly increasing the RSRP threshold due to the limitedduration. Subsequently the system performance may deteriorate. Finally,higher-priority transmission might require higher values of X whencompared to lower-priority transmission in order to reduce theprobability of collision.

In this disclosure, techniques are provided to dynamically adjust the X%constraint on the number of resources in Step 1 that needs to be passedto Step 2 of the Mode 2 resource selection procedure. In particular,techniques are disclosed to iteratively adjust the X% in each of theStep 1 iterations to avoid passing resources that would result incollisions. In some embodiments, this is done by adapting the X% basedon the number of iterations, the priority, the CBR (channel busy ratio),CR (channel occupancy ratio), the PDB (packet delay budget), the ratiobetween the periodic and aperiodic traffic or a combination thereof. Inaddition, multiple values of X% may be configured based on priority,whereby for each priority up to two values of X% can be used (i.e., onefor the duration within the signaling window and the other for theduration of the resource selection window).

In some embodiments, the disclosed technology allows the values of X% tovary either by multiplication of a factor or by selection from apredefined set. The disclosed technology allows setting different valuesof {X1%, X2%} for each priority and thus offers higher flexibility tothe system by having different ratios for signaling and resourceselection windows.

According to some embodiments, the present technology presents severalbenefits:

-   Allows the adaptation of X% in each iteration of Step 1 of the Mode    2 resource selection procedure.-   Reduces the chances of passing resources that would result into    collisions to Step 2. This is done by dynamically reducing the X%    requirement based on priority, CBR, CR, etc.-   Offers different values of X% for signaling and resource selection    windows (e.g., X₁%, X₂%) based on priority. Note that the traffic    within the signaling window affected by X₁% will be mostly    aperiodic. Hence, the proposed technology offers an X₁% value based    on priority for aperiodic traffic.-   Protects higher priority traffic by reducing the chances of    interference from lower priority UEs. This is done by dynamically    reducing X% based on priority which would prevent Step 1 from    increasing the interference thresholds and subsequently preventing    low priority UEs from accessing some resources.-   Reduces the processing burden on low priority UEs by allowing Step 1    of the resource selection procedure to converge earlier.

Turning to FIG. 1 , a resource selection window 100 is depicted. Here,resource selection window 100 has two intervals, X₁ 106 and X₂ 108. Inany of the embodiments disclosed herein, maintaining separate minimalvalues of X% for each interval 106, 108 of the resource selection window100 may be implemented to allow for greater flexibility. X₁ 106 includesperiodic and aperiodic reservations, while X₂ 108 only includes periodicreservations. The aperiodic signaling limit 104 may be at slot 31.

In FIG. 1 , traffic is assumed to be aperiodic with a packet delaybudget (PDB) of 50 ms, thus there is a selection window of 100 slotshaving a slot duration of 0.5 ms. The time when resource selection istriggered by a trigger 102 is at slot n. Since most transmissions arelikely to be reserved by a previous transmission that is no more than 31slots before, all reservations that can affect the resource selectionresult will likely occur at slot m in the window [n-31, n]. Furthermore,such reservation reserves a resource at slot m + d with d in the range[0, 31]. Therefore, sensing information is mostly unavailable for 69slots and greater than 69% of the resources will be available in theselection regardless of the initial RSRP threshold and traffic load asdepicted in FIG. 1 .

Since m can be uniformly distributed in [n-31, n] and d can be uniformlydistributed in [0, 31], when a window is considered that contains allobservable reserved resources in the future, the window size is below 20slots in most of the cases. Correspondingly, if a window is consideredthat contains 90 percent of the observable reserved resources in thefuture, the window size is below 16 slots in most of the cases. As aresult, most of the time a RSRP increase step of 3 dB cannot betriggered, regardless of the traffic load, given that more than 80% ofresources in the selection window will be free by default. As a matterof fact, the RSRP threshold can only be triggered when UE approach theend of its Packet Delay Budget (PDB) as the UE shrinks its resourceselection window. This has the equivalent effect of limiting the PDB ofthe traffic to below 31 slots, or in this case, to below 16 slots, giventhe above observations and the fact that current resource free thresholdis 20 percent. It is likely that system performance may be heavilypenalized under heavy or bursty traffic. This issue does not apply forperiodic traffic.

Turning to FIG. 2A, the following Mode 2 resource selection procedure200 is used. The first step may be to set a selection window 202. Acandidate single-slot resource for transmission R_(x,y) may be definedas a set of L_(subCH) contiguous sub-channels with sub-channel x+j inslot

t_(y)^(SL)

where j = 0,..., L_(subCH) - 1. The UE may assume that any set ofL_(subCH) contiguous sub-channels included in the corresponding resourcepool within the time interval [n + T₁, n + T₂] correspond to onecandidate single-slot resource, where selection of T₁ is up to UEimplementation under 0 ≤ T₁ ≤ T_(proc,1), where T_(proc,1) is open todefinition; If T_(2min) is shorter than the remaining packet delaybudget (in slots) then T₂ is up to UE implementation subject to T_(2min)≤ T₂ ≤ remaining packet budget (in slots); otherwise, T₂ is set to theremaining packet delay budget (in slots). The total number of candidatesingle-slot resources may be denoted by M_(total) or M_(t).

At step 204, the sensing window is defined by the range of slots [n -T₀, n- T_(proc,0)) where T₀ is defined above and T_(proc,0) is open todefinition. The UE may monitor slots which can belong to a sidelinkresource pool within the sensing window except for those in which itsown transmissions occur. The UE may perform the behavior in thefollowing steps based on the decoded PSCCH and the measured RSRP inthese slots.

At step 206, the internal threshold parameter Th(p_(i)) is set to thecorresponding value from the higher layer parameter SL-ThresRSRP_pi_pjfor p_(j) equal to the given value of prio_(TX) and each priority valuep_(i).

At step 208, the set S_(A) is initialized to the set of all thecandidate single-slot resources.

At step 210, the UE may exclude any restricted resources (e.g. due tohalf-duplex constraint). The UE may exclude any candidate single-slotresource R_(x,y) from the set S_(A) if it meets one, multiple, or all ofthe following conditions:

-   The UE has not monitored slot-   t_(m)^(SL)-   in step 204.-   For any periodicity value allowed by the higher layer parameter    reservationPeriodAllowed and a hypothetical SCI format 0-1 received    in slot-   t_(m)^(SL)-   with “Resource reservation period” field set to that periodicity    value and indicating all subchannels of the resource pool in this    slot, condition c in step 212 would be met.

At step 212, the UE may exclude resources if occupied by a UE where thecorresponding RSRP is above the threshold. Resources occupied by ahigher priority UE usually have a lower threshold. While resourcesoccupied by a lower priority UE usually have a higher threshold. Soresources occupied by a UE with lower priority or higher priority mayalso be excluded if the RSRP is above the threshold (Th). The UE mayexclude any candidate single-slot resource R_(x,y) from the set S_(A) ifit meets the following conditions:

-   a. the UE receives an SCI format 0-1 in slot-   t_(m)^(SL),-   and “Resource reservation period” field, if present, and “Priority”    field in the received SCI format 0-1 indicate the values P_(rsvp_RX)    and prio_(RX), respectively according to step 204;-   b. the RSRP measurement performed, according to received SCI format    0-1, is higher than Th(prio_(RX));-   c. the SCI format received in slot-   t_(m)^(SL)-   or the same SCI format which, if and only if the “Resource    reservation period” field is present in the received SCI format 0-1,    is assumed to be received in slot(s)-   t_(m + q × p_(rsvp_RX)^(′))^(SL)-   determines according to step 204 the set of resource blocks and    slots which overlaps with-   R_(x, y + j × p_(rsvp_TX)^(′))-   for q=1, 2, ..., Q and j=0, 1, ..., C_(resel) - 1. Here,-   P^(′)_(rsvp_RX)-   is P_(rsvp_) _(RX) converted to units of logical slots,-   $Q = \left\lceil \frac{T_{scal}}{P_{rsvp\_ RX}} \right\rceil$-   if P_(rsvp_RX) < T_(scal) and-   n^(′) − m ≤ P^(′)_(rsvp_RX),-   where-   t_(n^(′))^(SL) = n-   if slot n belongs to the set-   (t₀^(SL), t₁^(SL), …, t_(T_(max))^(SL)),-   otherwise slot-   t_(n^(′))^(SL)-   is the first slot after slot n belonging to the set-   (t₀^(SL), t₁^(SL), …, t_(T_(max))^(SL));-   otherwise Q = 1. T_(scal) may be decided according to 3GPP 38.214.

At step 221, if the number of candidate single-slot resources remainingin the set S_(A) is smaller than X · M_(total), then at step 214Th(p_(i)) is increased by a given number (e.g. 1 dB, 2 dB, 3 dB, 4 dB, 5dB, 6 dB, 7 dB, 8 dB, 9 dB, 10 dB, or 11 dB-100 dB) for each priorityvalue Th(p_(i)) and the procedure continues with step 208. An iterationmay be defined as each time the procedure/UE/processor determines thatthe remaining candidates in S_(A) is smaller than X · M_(total) and hasto loop back to step 208 via step 214. X varies dynamically for eachiteration based on iteration number and/or priority of the transmission.For example, X may be either 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%,50%, 55%, 60%, 65%, 70%, or 75% based on priority.

At step 221, the minimum value(s) for the ratio (e.g.., X or {X₁, X₂} ifportions of the resource selection window are considered separately)varies dynamically in each iteration. The factor by which the value(s)of X changes may depend on the iteration number and/or the priority ofthe transmission that triggered the resource selection.

In each iteration of the resource selection procedure, the value of Xmay be dynamically adjusted by a given factor. The factor may be eitherfixed or pre-configured. The factor may depend on the priority of thetransmission that triggered a resource selection. The factor may changedepending on an iteration number (e.g., reduce by 1% for the firstiteration and 2% for the second iteration). The factor may havedifferent values for different portions of the resource selectionwindows. In particular, consider a case in which two ratios are to bepreserved, one for a portion of the resource selection window and theother for the full selection window; e.g.., X₁ and X₂. The decreasingfactor can be different for the two ratios, thus resulting in tworespectively different decreasing rates for X₁ and X₂. The two factorsmay also depend on the priority of the transmission that triggered theresource selection.

At step 214, the UE may increase RSRP thresholds by the given numberwhen at least one of the following conditions holds:

-   a. If the number of candidate single-slot resources remaining in the    set S_(A) is less than 0.5 · M_(total)-   b. The total number of candidate single-slot resources within [n +    T1, n+ 16] is denoted by M_(total), aperiodic. If the number of    candidate single-slot resources remaining in the set S_(A) that is    within [n+T1, n+ 16] is less than 0.5 · M_(total), _(aperioidic).

At step 216, if the number of candidate single-slot resources remainingin the set S_(A) is greater than or equal to X · M_(total), the UE mayreport remaining of set S_(A) to one or more higher layers, and the oneor more high layers may randomly select a candidate resource fortransmission.

Turning to FIG. 2B, at step 222 the minimum value(s) for the ratio(e.g., X or {X₁, X₂} if portions of the resource selection window areconsidered separately) varies dynamically in each iteration, whereby thevalue(s) of X is selected from a fixed/preconfigured set. The valueswithin the set(s) may depend on the priority of the transmission thattriggered the resource selection.

In each iteration of the resource selection procedure, the value of Xmay be changed based on an index of the iteration based on afixed/preconfigured set of possible values.

Different sets may be defined depending on the priority of thetransmission that triggered the resource selection.

Different sets may be defined for different portions of the resourceselection window. For example, two ratios might be preserved in somecases (one for a portion of the resource selection window, X₁, and theother for the full selection window, X₂). A different set of values maybe maintained for each ratio. The sets may also depend on the priorityof the transmission that triggered the resource selection.

In FIG. 3A, at step 223, the minimum value(s) for the ratio (e.g., X or{X₁, X₂} if portions of the resource selection window are consideredseparately) varies dynamically in each iteration. The factor by whichthe value(s) of X changes may depend on the CBR or the ratio ofaperiodic/periodic traffic or the ratio X₁/PDB or a combination thereof.

The factor by which the value of X is changed in each iteration may varymay be based on the network congestion and/or the traffic type. Inparticular, any one of the following (or a combination thereof) may bethe parameters that impact the factor by which X is changed:

a. The value of the channel busy ratio (CBR) that may be observed overthe resource pool. In particular, a high CBR indicates that thesubchannels are highly occupied. Thus, for example, the factor affectingthe value of X may be set lower for low priority traffic and at the sametime set higher for the high-priority traffic (e.g., 1% reduction forhigh-priority traffic and 5% reduction for low-priority traffic). Thismay result in a higher value of X for high-priority traffic and lowervalue of X for lower-priority traffic thus reducing the observedinterference on higher-priority traffic by a lower value of X forlower-priority traffic at the expense of higher number of collisions forlower-priority traffic.

b. Since different traffic types may be identified by a UE afterdecoding the SCI, a UE may calculate a ratio between aperiodic andperiodic traffic. However, due to the limitation of the SCI signalingcapability (32-slot window), a UE may not be able to detect the presenceof aperiodic traffic beyond the SCI signaling window. Hence, a highaperiodic/periodic ratio may indicate that the sensing information islimited and is not indicative of the resource reservation beyond the32-slot SCI signaling window. Subsequently, the factors by which thevalues of X are changed may be adjusted for different priority traffictypes based on the aperiodic/periodic ratio to provide favorable accessto certain priorities. For example, the factor by which the value of Xis changed may be set higher for higher-priority traffic and reduced forlower-priority traffic. Hence, this provides the higher-priority trafficwith more access to the available resources.

c. The ratio of X₁/PDB. When this ratio is high, it indicates that theUE is aware of all the reserved resources by all traffic types even whenthe system is highly occupied by aperiodic traffic. Hence, the factor bywhich the value of X may be changed may be adjusted accordingly. Forexample, for high-priority traffic with high X₁/PDB, the factor by whichthe value of X may be changed may be set higher to allow better accessto the available resources because the UE is aware of all resourcereservations and it is approaching its PDB.

In FIG. 3B, at step 224, the minimum values for the ratios (e.g., {X₁,X₂}) may vary in each iteration. The factors by which the values of X₁and X₂ change may depend on the CR (channel occupancy ratio) of the UE.

In each iteration of the resource selection procedure, when portions ofthe resource selection window are considered separately, e.g., X₁ andX₂, the value(s) of X₁ and X₂ may be changed based on the channeloccupancy ratio (CR) of a given UE. In particular, a UE may setdifferent factors for X₁, X₂. For example, a UE approaching itsCR_(Limit) may decrease the factor by which X₁ may be changed whileincreasing the factor by which X₂ may be changed. Subsequently, the UEmay have a low value of X₁ and a high value of X₂ thus pushing upcomingreservations further in the future in order to reduce its CR value.

In FIG. 4 , at step 225, the UE or resource selection procedure mayinitialize different minimum candidate resources ratios, (e.g., X or{X₁, X₂} if portions of the resource selection window are consideredseparately) for different traffic priorities.

In some scenarios, it might be beneficiary to have different initialvalues of X for different traffic priorities. In particular, setting ahigher value of X for resource selection enforces the procedure tocreate a larger set of candidate resources to the higher layers forresource selection. This helps the UE in maintaining the chain integrityand reducing the potential for collision at the expense of higher RSRPthresholds. Hence, the system performance may be improved byinitializing the resource selection procedure by different values of X.Additionally the factor by which the value of X changes in eachiteration may also depend on the priorities as discussed in Solutions 1and 2, thus providing the highest flexibility to the system.

One important aspect of resource selection for Mode 2 operation is aminimum number of candidate resources (expressed as a ratio with respectto the total resources within the selection window) that are passed to ahigher layer for resource selection. In some embodiments, the followingcriteria may be used:

-   In Step 1 of the Mode 2 resource selection procedure, when the ratio    of identified candidate resources to the total number of resources    in a resource selection window is less than X%, all configured    thresholds are increased by 3 dB and the resource identification    procedure is repeated    -   X may be 20%, or 35%, or 50%.-   RSRP threshold increments do not depend on any other conditions

A minimum value of the ratio between the candidate resources that may beselected to the total number of resources within the resource selectionwindow may be defined as X% or X. In particular, if this ratio is setless than X%, the UE increases its threshold levels 214 in order toincrease the resources that can be indicated to the higher layers. Inaddition, the value of X may be preconfigured per pool per L1 (Layer 1which is the Physical Layer) priority from a set of 20%, 35% or 50%.

FIG. 5 illustrates a block diagram of an electronic device 501 in anetwork environment 500, according to one embodiment. Referring to FIG.5 , the electronic device 501 in the network environment 500 maycommunicate with another electronic device 502 via a first network 598(e.g., a short-range wireless communication network), or anotherelectronic device 504 or a server 508 via a second network 599 (e.g., along-range wireless communication network). The electronic device 501may also communicate with the electronic device 504 via the server 508.The electronic device 501 may include a processor 520, a memory 530, aninput device 550, a sound output device 555, a display device 560, anaudio module 570, a sensor module 576, an interface 577, a haptic module579, a camera module 580, a power management module 588, a battery 589,a communication module 590, a subscriber identification module (SIM)596, or an antenna module 597. In one embodiment, at least one (e.g.,the display device 560 or the camera module 580) of the components maybe omitted from the electronic device 501, or one or more othercomponents may be added to the electronic device 501. In one embodiment,some of the components may be implemented as a single integrated circuit(IC). For example, the sensor module 576 (e.g., a fingerprint sensor, aniris sensor, or an illuminance sensor) may be embedded in the displaydevice 560 (e.g., a display).

The processor 520 may execute, for example, software (e.g., a program540) to control at least one other component (e.g., a hardware or asoftware component) of the electronic device 501 coupled with theprocessor 520, and may perform various data processing or computations.As at least part of the data processing or computations, the processor520 may load a command or data received from another component (e.g.,the sensor module 576 or the communication module 590) in volatilememory 532, process the command or the data stored in the volatilememory 532, and store resulting data in non-volatile memory 534. Theprocessor 520 may include a main processor 521 (e.g., a centralprocessing unit (CPU) or an application processor (AP)), and anauxiliary processor 510 (e.g., a graphics processing unit (GPU), animage signal processor (ISP), a sensor hub processor, or a communicationprocessor (CP)) that may be operable independently from, or inconjunction with, the main processor 521. Additionally or alternatively,the auxiliary processor 510 may be adapted to consume less power thanthe main processor 521, or execute a particular function. The auxiliaryprocessor 510 may be implemented as being separate from, or a part of,the main processor 521.

The auxiliary processor 510 may control at least some of the functionsor states related to at least one component (e.g., the display device560, the sensor module 576, or the communication module 590) among thecomponents of the electronic device 501, instead of the main processor521 while the main processor 521 may be in an inactive (e.g., sleep)state, or together with the main processor 521 while the main processor521 may be in an active state (e.g., executing an application).According to one embodiment, the auxiliary processor 510 (e.g., an imagesignal processor or a communication processor) may be implemented aspart of another component (e.g., the camera module 580 or thecommunication module 590) functionally related to the auxiliaryprocessor 510.

The memory 530 may store various data used by at least one component(e.g., the processor 520 or the sensor module 576) of the electronicdevice 501. The various data may include, for example, software (e.g.,the program 540) and input data or output data for a command relatedthereto. The memory 530 may include the volatile memory 532 or thenon-volatile memory 534.

The program 540 may be stored in the memory 530 as software, and mayinclude, for example, an operating system (OS) 542, middleware 544, oran application 546.

The input device 550 may receive a command or data to be used by othercomponent (e.g., the processor 520) of the electronic device 501, fromthe outside (e.g., a user) of the electronic device 501. The inputdevice 550 may include, for example, a microphone, a mouse, or akeyboard.

The sound output device 555 may output sound signals to the outside ofthe electronic device 501. The sound output device 555 may include, forexample, a speaker or a receiver. The speaker may be used for generalpurposes, such as playing multimedia or recording, and the receiver maybe used for receiving an incoming call. According to one embodiment, thereceiver may be implemented as being separate from, or a part of, thespeaker.

The display device 560 may visually provide information to the outside(e.g., a user) of the electronic device 501. The display device 560 mayinclude, for example, a display, a hologram device, or a projector andcontrol circuitry to control a corresponding one of the display,hologram device, and projector. According to one embodiment, the displaydevice 560 may include touch circuitry adapted to detect a touch, orsensor circuitry (e.g., a pressure sensor) adapted to measure theintensity of force incurred by the touch.

The audio module 570 may convert a sound into an electrical signal andvice versa. According to one embodiment, the audio module 570 may obtainthe sound via the input device 550, or output the sound via the soundoutput device 555 or a headphone of an external electronic device 502directly (e.g., wired) or wirelessly coupled with the electronic device501.

The sensor module 576 may detect an operational state (e.g., power ortemperature) of the electronic device 501 or an environmental state(e.g., a state of a user) external to the electronic device 501, andthen generate an electrical signal or data value corresponding to thedetected state. The sensor module 576 may include, for example, agesture sensor, a gyro sensor, an atmospheric pressure sensor, amagnetic sensor, an acceleration sensor, a grip sensor, a proximitysensor, a color sensor, an infrared (IR) sensor, a biometric sensor, atemperature sensor, a humidity sensor, or an illuminance sensor.

The interface 577 may support one or more specified protocols to be usedfor the electronic device 501 to be coupled with the external electronicdevice 502 directly (e.g., wired) or wirelessly. According to oneembodiment, the interface 577 may include, for example, a highdefinition multimedia interface (HDMI), a universal serial bus (USB)interface, a secure digital (SD) card interface, or an audio interface.

A connecting terminal 578 may include a connector via which theelectronic device 501 may be physically connected with the externalelectronic device 502. According to one embodiment, the connectingterminal 578 may include, for example, an HDMI connector, a USBconnector, an SD card connector, or an audio connector (e.g., aheadphone connector).

The haptic module 579 may convert an electrical signal into a mechanicalstimulus (e.g., a vibration or a movement) or an electrical stimuluswhich may be recognized by a user via tactile sensation or kinestheticsensation. According to one embodiment, the haptic module 579 mayinclude, for example, a motor, a piezoelectric element, or an electricalstimulator.

The camera module 580 may capture a still image or moving images.According to one embodiment, the camera module 580 may include one ormore lenses, image sensors, image signal processors, or flashes.

The power management module 588 may manage power supplied to theelectronic device 501. The power management module 588 may beimplemented as at least part of, for example, a power managementintegrated circuit (PMIC).

The battery 589 may supply power to at least one component of theelectronic device 501. According to one embodiment, the battery 589 mayinclude, for example, a primary cell which may be not rechargeable, asecondary cell which may be rechargeable, or a fuel cell.

The communication module 590 may support establishing a direct (e.g.,wired) communication channel or a wireless communication channel betweenthe electronic device 501 and the external electronic device (e.g., theelectronic device 502, the electronic device 504, or the server 508) andperforming communication via the established communication channel. Thecommunication module 590 may include one or more communicationprocessors that are operable independently from the processor 520 (e.g.,the AP) and supports a direct (e.g., wired) communication or a wirelesscommunication. According to one embodiment, the communication module 590may include a wireless communication module 592 (e.g., a cellularcommunication module, a short-range wireless communication module, or aglobal navigation satellite system (GNSS) communication module) or awired communication module 594 (e.g., a local area network (LAN)communication module or a power line communication (PLC) module). Acorresponding one of these communication modules may communicate withthe external electronic device via the first network 598 (e.g., ashort-range communication network, such as Bluetooth™, wireless-fidelity(Wi-Fi) direct, or a standard of the Infrared Data Association (IrDA))or the second network 599 (e.g., a long-range communication network,such as a cellular network, the Internet, or a computer network (e.g.,LAN or wide area network (WAN)). These various types of communicationmodules may be implemented as a single component (e.g., a single IC), ormay be implemented as multiple components (e.g., multiple ICs) that areseparate from each other. The wireless communication module 592 mayidentify and authenticate the electronic device 501 in a communicationnetwork, such as the first network 598 or the second network 599, usingsubscriber information (e.g., international mobile subscriber identity(IMSI)) stored in the subscriber identification module 596.

The antenna module 597 may transmit or receive a signal or power to orfrom the outside (e.g., the external electronic device) of theelectronic device 501. According to one embodiment, the antenna module597 may include one or more antennas, and, therefrom, at least oneantenna appropriate for a communication scheme used in the communicationnetwork, such as the first network 598 or the second network 599, may beselected, for example, by the communication module 590 (e.g., thewireless communication module 592). The signal or the power may then betransmitted or received between the communication module 590 and theexternal electronic device via the selected at least one antenna.

At least some of the above-described components may be mutually coupledand communicate signals (e.g., commands or data) therebetween via aninter-peripheral communication scheme (e.g., a bus, a general purposeinput and output (GPIO), a serial peripheral interface (SPI), or amobile industry processor interface (MIPI)).

According to one embodiment, commands or data may be transmitted orreceived between the electronic device 501 and the external electronicdevice 504 via the server 508 coupled with the second network 599. Eachof the electronic devices 502 and 504 may be a device of a same type as,or a different type, from the electronic device 501. All or some ofoperations to be executed at the electronic device 501 may be executedat one or more of the external electronic devices 502, 504, or server508. For example, if the electronic device 501 should perform a functionor a service automatically, or in response to a request from a user oranother device, the electronic device 501, instead of, or in additionto, executing the function or the service, may request the one or moreexternal electronic devices to perform at least part of the function orthe service. The one or more external electronic devices receiving therequest may perform the at least part of the function or the servicerequested, or an additional function or an additional service related tothe request, and transfer an outcome of the performing to the electronicdevice 501. The electronic device 501 may provide the outcome, with orwithout further processing of the outcome, as at least part of a replyto the request. To that end, a cloud computing, distributed computing,or client-server computing technology may be used, for example.

One embodiment may be implemented as software (e.g., the program 540)including one or more instructions that are stored in a storage medium(e.g., internal memory 536 or external memory 538) that may be readableby a machine (e.g., the electronic device 501). For example, a processorof the electronic device 501 may invoke at least one of the one or moreinstructions stored in the storage medium, and execute it, with orwithout using one or more other components under the control of theprocessor. Thus, a machine may be operated to perform at least onefunction according to the at least one instruction invoked. The one ormore instructions may include code generated by a complier or codeexecutable by an interpreter. A machine-readable storage medium may beprovided in the form of a non-transitory storage medium. The term“non-transitory” indicates that the storage medium may be a tangibledevice, and does not include a signal (e.g., an electromagnetic wave),but this term does not differentiate between where data may besemi-permanently stored in the storage medium and where the data may betemporarily stored in the storage medium.

According to one embodiment, a method of the disclosure may be includedand provided in a computer program product. The computer program productmay be traded as a product between a seller and a buyer. The computerprogram product may be distributed in the form of a machine-readablestorage medium (e.g., a compact disc read only memory (CD-ROM)), or bedistributed (e.g., downloaded or uploaded) online via an applicationstore (e.g., Play Store™), or between two user devices (e.g., smartphones) directly. If distributed online, at least part of the computerprogram product may be temporarily generated or at least temporarilystored in the machine-readable storage medium, such as memory of themanufacturer’s server, a server of the application store, or a relayserver.

According to one embodiment, each component (e.g., a module or aprogram) of the above-described components may include a single entityor multiple entities. One or more of the above-described components maybe omitted, or one or more other components may be added. Alternativelyor additionally, a plurality of components (e.g., modules or programs)may be integrated into a single component. In this case, the integratedcomponent may still perform one or more functions of each of theplurality of components in the same or similar manner as they areperformed by a corresponding one of the plurality of components beforethe integration. Operations performed by the module, the program, oranother component may be carried out sequentially, in parallel,repeatedly, or heuristically, or one or more of the operations may beexecuted in a different order or omitted, or one or more otheroperations may be added.

Although certain embodiments of the present disclosure have beendescribed in the detailed description of the present disclosure, thepresent disclosure may be modified in various forms without departingfrom the scope of the present disclosure. Thus, the scope of the presentdisclosure may not be determined merely based on the describedembodiments, but rather determined based on the accompanying claims andequivalents thereto.

What is claimed is: 1-20. (canceled)
 21. A method of resource selection,the method comprising: decoding, by a UE, a physical sidelink controlchannel (PSCCH) and measuring a reference signal received power (RSRP);comparing, by the UE, the RSRP with a threshold; defining a set of atotal number of resources within a selection window; excluding, by theUE and based on at least one of a result of decoding the PSCCH or aresult of comparing the RSRP with the threshold, one or more resourcesfrom the total number of resources; and determining, by the UE, whethera number of remaining resources, after excluding the one or moreresources from the total number of resources, is greater than or equalto a percentage of the total number of resources, wherein the percentageis selected from a preconfigured set, based on a traffic priority. 22.The method of claim 21 further comprising reporting the number ofremaining resources to a higher layer based on the number of remainingresources being greater than or equal to the percentage of the totalnumber of resources.
 23. The method of claim 21 further comprising:increasing the threshold, in a first iteration based on the number ofremaining resources being less than the percentage of the total numberof resources; and redetermining, in the first iteration, whether asubsequent number of remaining resources is greater than or equal to asubsequent percentage of the total number of resources.
 24. The methodof claim 23, wherein the subsequent percentage varies from the firstiteration to a second iteration, wherein a factor by which thesubsequent percentage changes depends on an iteration number or atransmission priority.
 25. The method of claim 23, wherein thesubsequent percentage varies from the first iteration to a seconditeration, and the subsequent percentage is selected from thepreconfigured set, wherein the subsequent percentage is based on apriority of a transmission that triggered the resource selection. 26.The method of claim 23, wherein the subsequent percentage varies fromthe first iteration to a second iteration, wherein a factor by which thesubsequent percentage changes depends on a channel busy ratio (CBR) or aratio between aperiodic and periodic traffic.
 27. The method of claim23, wherein the selection window is divided into at least a firstsection with a first percentage and a second section with a secondpercentage, wherein the first percentage and the second percentage varyfrom the first iteration to a second iteration, respectively.
 28. Themethod of claim 21, wherein the one or more resources are occupied bythe UE and a corresponding RSRP of the one or more resources is greaterthan or equal to the threshold.
 29. The method of claim 21, wherein theselection window is divided into at least a first section with a firstpercentage and a second section with a second percentage.
 30. A systemfor resource selection, comprising: a processor; and a memory storingnon-transitory processor-executable instructions that, when executed bythe processor, cause the processor to: decode a physical sidelinkcontrol channel (PSCCH) and measuring a reference signal received power(RSRP); compare the RSRP with a threshold; define a set of a totalnumber of resources within a selection window; exclude, based on atleast one of a result of decoding the PSCCH or a result of comparing theRSRP with the threshold, one or more resources from the total number ofresources; and determine whether a number of remaining resources, afterexcluding the one or more resources from the total number of resources,is greater than or equal to a percentage of the total number ofresources, wherein the percentage is selected from a preconfigured set,based on a traffic priority.
 31. The system of claim 30, wherein theinstructions further cause the processor to report the number ofremaining resources to a higher layer based on the number of remainingresources being greater than or equal to the percentage of the totalnumber of resources.
 32. The system of claim 31, wherein theinstructions further cause the processor to: increase the threshold, ina first iteration, based on the number of remaining resources being lessthan the percentage of the total number of resources; and redetermine,in the first iteration, whether a subsequent number of remainingresources is greater than or equal to a subsequent percentage of thetotal number of resources.
 33. The system of claim 32, wherein thesubsequent percentage varies from the first iteration to a seconditeration, wherein a factor by which the subsequent percentage changesdepends on an iteration number or a transmission priority.
 34. Thesystem of claim 32, wherein the subsequent percentage varies from thefirst iteration to a second iteration, and the subsequent percentage isselected from the preconfigured set, wherein the subsequent percentageis based on a priority of a transmission that triggered the resourceselection.
 35. The system of claim 32, wherein the subsequent percentagevaries from the first iteration to a second iteration, wherein a factorby which the subsequent percentage changes depends on a channel busyratio (CBR) or a ratio between aperiodic and periodic traffic.
 36. Thesystem of claim 32, wherein the selection window is divided into atleast a first section with a first percentage and a second section witha second percentage, wherein the first percentage and the secondpercentage vary from the first iteration to a second iteration,respectively.
 37. The system of claim 32, wherein the one or moreresources are occupied by a UE and a corresponding RSRP of the one ormore resources is greater than or equal to the threshold.
 38. The systemof claim 32, wherein the selection window is divided into at least afirst section with a first percentage and a second section with a secondpercentage.